Comparing all string vs first letter

main_test.go

package main

import (
	"bufio"
	"os"
	"testing"
)

var ret = ""

func getWords() []string {
	// 172k words
	f, _ := os.Open("wordlist.txt")
	defer f.Close()

	words := []string{}
	s := bufio.NewScanner(f)
	for s.Scan() {
		words = append(words, s.Text())
	}
	return words
}

var allWords []string = getWords()

func BenchmarkComparisonLongWord(b *testing.B) {
	r := ""
	for n := 0; n < b.N; n++ {
		for _, w := range allWords {
			if w == "banana" {
				r = "hi"
			} else {
				r = "no"
			}
		}
	}
	ret = r
}

func BenchmarkComparisonShortLetter(b *testing.B) {
	r := ""
	for n := 0; n < b.N; n++ {
		for _, w := range allWords {
			if w == "b" {
				r = "hi"
			} else {
				r = "no"
			}
		}
	}
	ret = r
}

func BenchmarkComparisonFirst(b *testing.B) {
	r := ""
	for n := 0; n < b.N; n++ {
		for _, w := range allWords {
			if w[0] == 'b' {
				r = "hi"
			} else {
				r = "no"
			}
		}
	}
	ret = r
}
$ go test -bench=. -benchmem main_test.go 

// goos: windows
// goarch: amd64
// cpu: AMD Ryzen 7 5800H with Radeon Graphics
// BenchmarkComparisonLongWord-16              5324            214208 ns/op               0 B/op          0 allocs/op
// BenchmarkComparisonShortLetter-16           9544            128170 ns/op               0 B/op          0 allocs/op
// BenchmarkComparisonFirst-16                10000            107055 ns/op               0 B/op          0 allocs/op
// PASS
// ok      command-line-arguments  3.627s